The invention relates to road paving machines, and more particularly to a screed assembly used in a road paving machine.
Road paving machines are used to deposit, spread, and compact an aggregate-filled tar-based paving material onto a prepared road bed to form a hard pavement surface. Road paving machines include a heavy metal plate called a screed plate that is used to level and compress newly deposited paving material into a compact layer.
The screed plates that are used in conventional road paving machines are usually coupled to a screed frame by a series of fasteners. The screed frame is connected to the rear end of the road paving machine frame.
A typical screed plate includes a curved leading edge that facilitates leveling the paving material and prevents accumulated paving material from overflowing onto the top of the screed plate. The curved leading edge of the screed plate is commonly positioned in a substantially vertical plane such that when the screed plate is coupled to the screed frame, the curved leading edge is positioned adjacent to a bottom surface on the screed frame. This interface between the screed plate and the screed frame is substantially planar which allows replacement screed plates to be easily manufactured and results in the interchangeability of the screed plates between different paving machines.
The above described screed assemblies are generally effective for leveling and compressing deposited paving material to form a paved road. Therefore, any improvement in the design or manufacture of such screed assemblies would be desirable.
The present invention is directed to a screed assembly for a road paving machine. The screed assembly levels and compresses newly deposited paving material into a compact layer over a prepared road bed.
The screed assembly of the present invention is configured with specialized mating components so that only appropriate replacement screed plates may be installed onto particular road paving machines. The mating components on the screed plate assembly of the present invention also prevent lateral movement of the screed plate relative to the screed frame when the screed plate is subjected to lateral impacts and forces during operation of the road paving machine. The components in the screed assembly are also easily manufactured and simply modified so that the mating components on the screed assembly may be varied from one road paving machine to another road paving machine. The screed plates are preferably configured such that the screed plates remain compatible with the screed frames on older road paving machines.
The screed assembly includes a screed plate and a screed frame. The screed plate includes a notch and the screed frame includes a tab that is inserted into the notch on the screed frame such that only screed plates and screed frames which include proper mating notches and tabs may be assembled together on road paving machines. In a preferred form of the invention, the width of the tab is approximately equal to the width of the notch to prevent lateral movement of the screed plate with respect to the screed frame when the screed plate is subjected to lateral impacts and forces during operation of the road paving machine.
The method of promoting the use of appropriate replacement screed plates on road paving machines includes: manufacturing a first screed plate that includes a first notch; manufacturing a first screed frame that includes a first tab which is inserted into the notch of the first screed plate when the first screed plate is assembled to the first screed frame; manufacturing a second screed plate that includes a second notch; manufacturing a second screed frame that includes a second tab which is inserted into the notch of the second screed plate when the second screed plate is assembled to the second screed frame, such that the first screed plate cannot be coupled to the second screed frame because the second tab on the second screed frame does not fit into the first notch on the first screed plate.